Screening and Optimization of Gas Sweetening Process Parameters with MDEA-PZ Solvent using Plackett-Burman Approach

Amine gas sweetening is a process in which acidic gases including hydrogen sulfide (H2S) and carbon dioxide (CO2) are removed by a solution of water and amines. Many parameters influence the sweetening process. Knowledge about the important parameters and their degree of importance is of great interest to achieve the optimum condition. Nine effective parameters including the CO2 and H2S contents of the feed, the temperature and pressure of the feed, the tray number and pressure of the absorber, the lean amine temperature, and the concentrations of Methyl Diethanol Amine (MDEA), and Piperazine (PZ) have been chosen as effective variables, while CO2/H2S recovery and total process energy have been considered as response variables.  After the verification of the present study with real plant data, the experimental layout was designed by the Plackett-Burman approach, and the model validation has been confirmed by ANOVA. The results of the present study showed that the most effective parameters in the CO2 recovery are the absorber tray number and PZ concentration, while in the H2S recovery, the absorber tray number is the most important variable. Regarding the total energy of the proces, feed temperature, PZ concentration, absorber tray number, lean amine temperature, and feed pressure are obtained as important variables. The optimum condition has been obtained in the feed and absorber pressures of 5758.9, and  1458.9 kPa respectively, with the feed and lean amine temperature of 0.11 and 50  respectively, the concentrations of 17.57 and 3.8 wt.% of MDEA and  PZ respectively, the absorber tray number of 20 and the mass flow rates of 792 and 103.6 kg/h of CO2 and H2S respectively. Under the mentioned conditions, the CO2 and H2S recovery were achieved at 99.99 % while the total energy of the process was 3.56 Mw.